Truss bridge in the context of "Callender-Hamilton bridge"

A bridge is a structure that crosses an obstacle such as a river, lake, railroad, road, or ravine. Its primary function is to transport vehicles, trains, and pedestrians, but bridges may also accommodate pipelines, buildings, wildlife, and canals. Basic structures used in bridge design include arches, trusses, beams, cantilevers, suspension cables, and cable-stays. Bridges are configured in a variety of forms, such as viaducts, aqueducts, trestles, movable bridges, double-deckers, pontoons, and portable military bridges. They may also be categorized by their materials, which include wood, brick, stone, iron, steel, and concrete.

The history of bridges reflects the evolution of humankind's engineering technologies. The Romans and ancient Chinese built major bridges of stone and timber. During the Renaissance, advances in science and engineering led to wider bridge spans and more elegant designs. Concrete was perfected in the early 1800s, and proved to be superior to stone in many regards. With the Industrial Revolution came mass-produced steel, which enabled the creation of suspension and cable-stayed bridges that could span wide obstacles.

A truss is an assembly of members such as beams, connected by nodes, that creates a rigid structure.

In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so that the assemblage as a whole behaves as a single object". A two-force member is a structural component where force is applied to only two points. Although this rigorous definition allows the members to have any shape connected in any stable configuration, architectural trusses typically comprise five or more triangular units constructed with straight members whose ends are connected at joints referred to as nodes.

The Kapellbrücke (from German 'Chapel Bridge') is a covered wooden footbridge spanning the river Reuss diagonally in the city of Lucerne in central Switzerland. Named after the nearby St. Peter's Chapel, the bridge is unique in containing a number of interior paintings dating back to the 17th century, although many of them were destroyed along with a larger part of the centuries-old bridge in a 1993 fire. Subsequently restored, the Kapellbrücke is the oldest wooden covered bridge in Europe, as well as the world's oldest surviving truss bridge. It serves as the city's symbol and as one of Switzerland's main tourist attractions.

A covered bridge is a timber-truss bridge with a roof, decking, and siding, which in most covered bridges create an almost complete enclosure. The purpose of the covering is to protect the wooden structural members from the weather. Uncovered wooden bridges typically have a lifespan of only 20 years because of the effects of rain and sun, but a covered bridge can last over 100 years. In the United States, only about 1 in 10 survived the 20th century. The relatively small number of surviving bridges is due to deliberate replacement, neglect, and the high cost of restoration.

Surviving covered bridges often attract touristic attention due to their rarity, quaint appearance, and bucolic settings. Many are considered historic and have been the subject of historic preservation campaigns.

The Nandu River Iron Bridge (Chinese: 海口南渡江铁桥), also known as the Devil's Iron Bridge, Old Iron Bridge, and originally the Lu Palace Bridge (吕宫桥), is a partially collapsed, steel truss bridge over the Nandu River, in the north of Hainan Province, China. Opened to traffic in 1942, it was Hainan's first bridge over the Nandu River.